I switched to using an LM317 adjustable voltage regulator for better performance and a simpler design. No more linear op amp.
I needed a power supply that could give out enough peak current to power at least three Raspberry Pi 2s. Just idle one Raspberry Pi 2 can draw almost 500 mA but at peak processing speed one can draw around 2 Amps at 5V. I didn’t want to have to have three “wall warts” so I sat down and did some research on the internet and designed the circuit below. With proper heat sinking on the 2N3055 power transistor it should allow for a peak of almost 7 Amps at 5V.